1. Field of the Invention
The invention relates to an electric motor system, preferably of the three-phase current design.
2. Discussion of Background Information
Electric motors are being used more and more in automotive engineering. Systems that handle the power exchange on the machine voltage level are known, such as the ISAD system (integrated starter-alternator-damper system).
Furthermore, electrically operated turbochargers are known, in which the power exchange also takes place on the machine voltage level. Thereby, the turbocharger capacity is derived entirely from the machine""s mains.
The aim of this invention is to create an electric motor system that can be used especially in automotive engineering environment, and that provides sufficient electric power or different levels of voltage for the supply of two different mains, especially for a turbocharger.
The electric motor system according to this invention is characterized by the fact that a first electric motor is provided, which is mechanically connected via the rotor thereof to a rotating shaft of an engine, especially of an internal combustion engine, that in addition, at least one second electric motor is provided, that the second electric motor is mechanically coupled via the rotor thereof to a rotating part of a mechanical aggregate, especially to a turbo-engine, and that the first electric motor is electrically coupled to at least the second electric motor in order to exchange electric power at a freely selectable voltage level. With this invention, it is possible for the first time to create a separate, autarkic, internal electric circuit or component that is independent from the voltage level of the machine""s mains. With this, the motor according to the invention and the electronic power circuits can be designed with optimal operating voltages. It is also known that it is usually more advantageous to transport electric power at higher voltages than those currently common in the machine""s mains.
This internal electrical circuit or component is connected with the first motor through electronic power components such as diodes and transistors and via circuits in accordance with the state of the art, in order to design the internal electrical component in terms of its electric ratios, such as voltages and currents and their time curves.
The first motor can supply and discharge mechanical torque via the combustion engine, so that the first motor can work as a generator when power is consumed, and it discharges this energy to the internal electrical part in the form of electric power. If the first motor draws electric power from the internal electric part, it works as a motor and can use this torque e.g. to start the combustion engine or to support or optimize its operation.
In a special feature of the invention, the first electric motor is mechanically connected via the rotor thereof to a rotating shaft or to the shaft of a combustion engine mechanically connected to the rotating shaft. As a result, the mechanical torque between the first electric motor and the combustion engine can easily be exchanged.
In accordance with one embodiment of the invention, the first electric motor is mechanically connected to the combustion engine via a gearbox. This design solution also improves the torque at low revs in an electrically driven turbocharger.
In accordance with another embodiment of the invention, the first electric motor is a part of the combustion engine, e.g. the rotor in the first electric motor is integrated in the flywheel of the combustion engine. The advantage of this design solution lies mainly in the fact that the entire arrangement can be produced in a relatively compact manner.
In accordance with a special feature of the invention, the first electric motor is connected to at least one external electric circuit, preferably a machine""s mains. This second electric coupling is connected to the machine""s mains via an electronic voltage adjustment circuit in accordance with the state of the art. As a result, power can be exchanged between the internal electric part and the machine""s mains. Thus, the first electric motor in accordance with the invention can be operated as a starter in one power direction and as a machine""s mains charging device in the other direction.
In accordance with a further embodiment of the invention, the first and second electric motors are mounted in a casing. With this embodiment, it is possible to produce an electric drive system that can be manufactured and used economically. The advantage of this invention is the fact that, unlike the known electromagnetic drives or purely mechanical drives, such as gears in which two different, usually independent speeds are required, major parts such as the casing elements, parts of the controls, can be spared. In addition, the well-known local EMC problems in the casing can be solved and do not penetrate into the surroundings.
In accordance with a further embodiment of the invention, the first and/or second electric motor(s) is/are designed as asynchronous, synchronous or reluctance motor. Thus, the optimal motor can be chosen for each individual application.
In accordance with a further feature of the invention, the first and second electric motors have rotors with the same axis of rotation. Especially in automotive engineering it is an advantage if there is only one axis of rotation for a mechanic-electric-mechanic coupling.
In accordance with a special embodiment of the invention, one of the two motors is designed as an inner rotor and the other motor as an outer rotor. This embodiment of the invention also allows a compact motor design.
In accordance with a further feature of the invention, the two electric motors have one mutual stator plate package. In this embodiment, a stator with at least one stator coil and at least two rotors can be provided in one casing. The rotors are mechanically separated, and each rotor has electromagnetic interaction with the electromagnetically active stator, whereby the rotor speeds may be the same or different.
In accordance with a further embodiment of the invention, the components for electric power exchange between the electric motors and/or an external electric circuit are mounted in the casing of at least one electric motor. This embodiment serves primarily to create a compact electric motor for automotive engineering environment.
In a further embodiment of the invention, the casing of at least one electric motor has a liquid cooling system. As a result, the frictional heat of the coils and also of the electronic power elements, which may occur due to the known problems with the high currents in the motor, can be discharged optimally.
In accordance with another feature of the invention, a mains connection with direct, alternating or three-phase current can be derived from the electric circuit connecting the two electric motors. In this embodiment, an additional three-phase, alternating or direct current network can be provided by the internal electric circuit. For example, a strong 230 V supply or 3xc3x97400 V supply can be decoupled, whereby the frequency can be specified either internally or externally. Thus, the machine""s mains and the aggregates connected to it are connected to this supply in terms of power via the internal electric circuit.
As a result, the combustion engine can be started from the power supply without requiring the machine""s mains, for example, or vice versa the combustion engine can support or charge an existing supply. It is also possible to charge the machine""s mains battery from the supply in a simple manner.
In accordance with a special feature of the invention, the stator of at least one electric motor has at least two winding systems, preferably separated galvanically within the motor, which are mechanically coupled with the motor""s main current. With this embodiment of the invention, it is possible to create two autarkic electric circuits with independent voltage levels. Another advantage of this invention is the fact that electromagnetic or EMC interference from switching in one winding system can be suppressed in another winding system. Moreover, the individual winding systems can work advantageously at different voltage levels, especially galvanically separate ones. Specific galvanic separation and/or a transformer for voltage adjustment between the two electric circuits involved is no longer required.
In accordance with a special feature of the invention, at least two winding systems are connected via separate electronic power switches with the relevant, preferably galvanically separated power circuits. This offers the advantage that for example a mains supply, especially a machine""s mains can be operated and controlled separately from another mains supply.
In accordance with a further embodiment of the invention, at least one winding system is connected via a rectifier bridge with a direct current or battery-fed mains, preferably a machine""s mains, for power exchange in one direction. With this embodiment, more economic, or even cheaper electronic power components can be used for charging.
In accordance with a further feature of the invention, at least one winding system is connected via a transistor bridge with a direct current or battery-fed mains, preferably a machine""s mains, for power exchange in both directions. This offers the advantage that a separate starter is not required, or power is drawn from one mains, preferably the machine""s mains, and fed into the other mains.
In accordance with a special feature of the invention, the motor with at least one of the winding systems can be operated as a generator for charging the connected machine""s mains, and also as a motor, preferably as a starter for a mechanically coupled combustion engine. This embodiment also offers the advantage that the starter, but also the generator can be eliminated in the design.
In accordance with a further embodiment of the design, galvanically separated electric power exchange via the at least two winding systems is possible between the electric circuits connected to the winding systems. This allows the advantageous separation of the machine""s mains from the second mains, which may well have a higher voltage.
In accordance with a further embodiment of the invention, the winding systems controlled via the electronically controlled switches take over the control of the electric parameters from winding systems coupled via non-controllable electronic power elements, preferably diodes. Thereby it is advantageous that for the control of the charging process no separate controllable elements are required and instead the controllable elements of the second mains can be used.
In accordance with a further feature of the invention, each winding systemxe2x80x94galvanically independent from the other winding systemxe2x80x94is connected with electromechanical function groups on generally different voltage levels. Thus, the electromechanical function groups, e.g. an electrically operated oil pump or water pump, or an electromagnetically operated valve control for in- and output valves or motor valves, or an electrically operated ventilator can be operated independent of the power limitation of the direct current or the battery at an advantageous voltage and/or current level.
In accordance with a special embodiment of the invention, an electromagnetic power exchange between the winding systems independent of rotor rotation according to the transformer principle is possible through close magnetic coupling of the winding systems. This offers the advantage that even when the rotor is stationary a power transfer to the relatively closely coupled other winding system is possible via a time-variable voltage through suitable electronic actuators on one winding system.
In accordance with a further feature of the invention, a slight electromagnetic influence on the winding systems results from weak magnetic coupling of the winding systems. This offers the advantage that electromagnetic interference due to switching processes in one winding system hardly takes effect in the other winding system.
In accordance with a further embodiment of the invention, a freely selectable electromagnetic power exchange between the winding systems and the rotor shaft can be achieved by controlling the electromagnetic parameters, preferably the currents and flux linking, of at least one winding system. This embodiment offers the advantage that mechanical and electric energy is provided in accordance with the current, optimal strategy.
In accordance with a further embodiment of the invention, a first and second electric motor is mounted in a casing. With this embodiment, it is possible to produce an electric drive system that can be manufactured and used economically. The advantage of this invention is the fact that, unlike the known electromagnetic drives or purely mechanical drives, such as gears in which two different, usually independent speeds are required, major parts such as the casing elements, parts of the controls, can be spared. In addition, the well-known local EMC problems in the casing can be solved and do not penetrate into the surroundings.
In accordance with a further embodiment of the invention, the first and/or second electric motor(s) is/are designed as asynchronous, synchronous or reluctance motor. Thus, the optimal motor can be chosen for each individual application.
In accordance with a further feature of the invention, the first and second electric motors have rotors with the same axis of rotation. Especially in automotive engineering environments it is an advantage if there is only one axis of rotation for a mechanic-electric-mechanic coupling.
The invention also provides for an electric motor system comprising at least a first electric motor comprising a first rotor. The first rotor is mechanically coupled to an engine. At least a second electric motor comprises a second rotor. The second rotor is mechanically coupled to a mechanical aggregate. An electronic power system is included. Each of the first electric motor and the second electric motor is electrically coupled to one another via the electronic power system in order to exchange electric power at a freely selectable voltage level.
At least one of the first and second motors may be of a three-phase type. The first rotor may be mechanically coupled to the engine via at least one rotating shaft. The engine may comprise an internal combustion engine. The first rotor may be mechanically coupled to the internal combustion engine via at least one rotating shaft. The second rotor may be mechanically coupled to the aggregate via a rotating part. The aggregate may comprise at least one of a turbo-engine and a turbocharger. The aggregate may comprise at least one of a turbo-engine and a turbocharger. The electric motor system may further comprise a gearbox, wherein the first electric motor is mechanically connected to the engine via the gearbox. The first electric motor may be at least one of integrated with the engine and integrated with a flywheel of the engine. The engine may comprise a flywheel and wherein the first electric motor is structurally integrated with the flywheel. The first electric motor may be connected to at least one of at least one external electric circuit, and a machine""s mains. The electric motor system may further comprise a casing, wherein each of the first and second motors are mounted in the casing. At least one of the first and second electric motors may be one of an asynchronous type motor, a synchronous type motor, and a reluctance type motor. An axis of the first rotor may be aligned with an axis of the second rotor, such that the first and second rotors of the first and second electric motors share a common axis of rotation. The first rotor may comprise one of an inner rotor and an outer rotor. The second rotor may comprise one of an inner rotor and an outer rotor. The first rotor may comprise an inner rotor and the second rotor may comprise an outer rotor.
The electric motor system may further comprise a mutual stator plate system. The mutual stator plate system may comprise at least one first stator and at least one second stator, the at least one first stator forming part of the first motor and the at least one second stator forming part of the second motor. Each of the first and second rotors may be rotatable with respect to the mutual stator plate system.
The electronic power system may comprise at least one of a component and an external electric circuit, which is mounted in a casing. The casing may contain at least one of the first and second motors. The electric motor system may further comprise a casing for housing at least one of the first and second motors, wherein the casing includes one of a cooling system and a liquid cooling system. The electronic power system may be capable of supplying to a mains connection at least one of a direct current, an alternating current, and a three-phase current.
Each of the first and second motors may comprise a stator, and wherein at least one of the stators includes at least two winding systems. The at least two winding systems may be galvanically separated from one another. The at least two winding systems may be coupled magnetically with a main flux of at least one of the first and second motors. The at least two winding systems may be connected to separate electronic power circuits. The separate electronic power circuits may be galvanically separated from one another. At least one of the at least two winding systems may be connected via a rectifier bridge to at least one of a direct current supply, a battery-fed mains, and a machine""s mains, whereby power can be exchanged in one direction. At least one of the at least two winding systems may be connected via a transistor bridge to at least one of a direct current supply, a battery-fed mains, and a machine""s mains, whereby power can be exchanged in both directions.
At least one of the first and second motors may be operated as a generator and as a motor. The generator may be configured to charge a connected machine""s mains.
A least one of the first and second motors can be operated as a generator and as a starter. The first motor may function as the generator and as the starter, and wherein the starter is mechanically coupled to the engine. Each of the at least two winding systems may be configured to allow a galvanically separable electric power exchange to occur between circuits connected to the winding systems. The at least two winding systems may be controllable via electronically controlled switches. The electronically controlled switches may be configured to take over control of electric parameters from the at least two winding systems. The at least two winding systems may be coupled to non-controllable electronic power elements. The non-controllable electronic power elements may comprise diodes.
Each of the at least two winding systems may be galvanically independent of the other winding system and may be connected with electromechanical function groups on generally different voltage levels. The at least two winding systems may be closely magnetically coupled such that an electromagnetic power exchange occurs between the at least winding systems independent of rotor rotation according to a transformer principle. The at least two winding systems may be weakly magnetically coupled such that a slight electromagnetic influence, results on the at least two winding systems. A freely selectable electromagnetic power exchange may occur between the at least two winding systems and a rotor shaft connected to one of the first and second rotors. The freely selectable electromagnetic power exchange may be adapted to occur by controlling electromagnetic parameters. The electromagnetic parameters may comprise at least one of currents and flux linking of at least one of the at least two winding systems. Each of the first and second electric motors may be mounted in a casing. Each of the first and second electric motors may comprise one of an asynchronous motor, a synchronous motor and a reluctance motor. Each of the first and second rotors may rotate with respect to a common axis.
The invention also provides for an electric motor system comprising at least a first electric motor comprising a first rotor and a first stator. The first rotor is mechanically coupled to an engine. At least a second electric motor comprises a second rotor and a second stator. The second rotor is mechanically coupled to a mechanical aggregate. The first stator is coupled to the second stator. An electronic power system is included. Each of the first electric motor and the second electrical motor is electrically coupled to one another via the electronic power system in order to exchange electric power at a freely selectable voltage level.
The invention still further provides for an electric motor system comprising a casing and at least a first electric motor comprising a first rotor and a first stator system. The first rotor is mechanically coupled to an engine. At least a second electric motor comprises a second rotor and a second stator system. The second rotor is mechanically coupled to a mechanical aggregate. The first stator is coupled to the second stator. Each of the first stator system and the second stator system is coupled to the casing. An electronic power system is provided. Each of the first rotor and the second rotor rotate about a common axis and each of the first electric motor and the second electrical motor is electrically coupled to one another via the electronic power system in order to exchange electric power at a freely selectable voltage level.